REM Sleep Behavior Disorder is a loss of muscle atonia which occurs normally during REM sleep. Without the paralysis that is not only normal but necessary, the result is that people act out their dreams to a varying degree. There may be minor muscle twitches, violent moviments and complex behaviours, such as screaming, shouting, kicking, punching, flailing the arms. The recalled dream is frequently vivid and violent.

When first described 30 years ago, it was thought as a curious experiment of nature, as many neurological and psychiatric diseases. It has now become a biomarker for the future development of one of the alfa-synucleinopathies: Parkinson’s, Lewy Body Dementia, Multiple System Atrophy or Pure Autonomic Failure. It is very common: 98% of people with polysomnography-proven RBD have biopsy proven disease. It is now considered as the marker of the onset of one of these diseases. Physicians need to look carefully for other clinical signs and symptoms. It may take 10-20 years for the full blown disease to become manifest.

Even in patients who have the sleep disorder provoked by antidepressants or adrenergic blockers, it is now thought that the alfa-synucleinopathy is installed. It may be diagnosed with the RBD Screening Questionnaire.

Stiasny Koster et al. Movement Disorders 2007, 22:2386-2393

Mahoswald and Schenk. Neurology 2018, 91:435-436

Pagano et al. Neurology 2018, 91:e894-e905

Patients may be evaluated with special emphasis on sleep, with actigraphy, in signs of cerebral involvement with functional and structural neuroimaging, Digital EEG with spectral analysis. Very careful neurological examination is mandatory.

Dr Paulo Bittencourt

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